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regularly supplied to the animal, they may be partly derived 

 from portions of this supply which have recently entered the 

 blood from the digestive organs, and which have not yet 

 become completely assimilated. When the animal has been 

 stinted in its supply of food, or altogether deprived of this, 

 the combustible elements to be consumed by this function 

 of respiration must be derived from the materials of which 

 the living body of the animal has consisted ; and thus that 

 emaciation be produced which is the known result of starva- 

 tion, or an insufficient supply of food. 



The non-azotized aliments, containing both these combus- 

 tible elements, viz., carbon and hydrogen, are well adapted 

 (independently of their directly nutritive properties) to 

 subserve, indirectly, the nutritive function, by supplying 

 some portion of the materials required for the function of 

 respiration, and thus preventing a too rapid consumption 

 of the tissues of the living body, by the oxygen which is 

 inhaled at each breath ; but it is not to be supposed that 

 non-azotized food exclusively is subservient to this important 

 office, which we have thus endeavoured to explain ; but that, 

 in this, all alimentary substances take a share ; for all are 

 rich in carbon and hydrogen, the important elements for this 

 purpose. 



In conclusion, I would remark that innumerable applica- 

 tions of vegetable substances, rendering them subservient to 

 the comfort or luxury of animals, more particularly man, 

 might be mentioned, but which are not dwelt upon here, 

 as not being relations of that essential nature to which 

 our present subject alone refers. Such, for instance, are 

 the use of timber in the construction of our houses, or 

 of vegetable drugs for the cure of our diseases. Had 

 we no timber, we might substitute stone or metal ; had 

 we no vegetable drugs, we might depend upon mineral 

 remedies or the unaided efforts of nature. But were 



